.TH std::deque::operator[] 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::deque::operator[] \- std::deque::operator[]

.SH Synopsis
   reference operator[]( size_type pos );             \fB(1)\fP
   const_reference operator[]( size_type pos ) const; \fB(2)\fP

   Returns a reference to the element at specified location pos. No bounds checking is
   performed.

.SH Parameters

   pos - position of the element to return

.SH Return value

   Reference to the requested element.

.SH Complexity

   Constant.

.SH Notes

   Unlike std::map::operator[], this operator never inserts a new element into the
   container. Accessing a nonexistent element through this operator is undefined
   behavior.

.SH Example

   The following code uses operator[] to read from and write to a std::deque<int>:


// Run this code

 #include <deque>
 #include <iostream>

 int main()
 {
     std::deque<int> numbers{2, 4, 6, 8};

     std::cout << "Second element: " << numbers[1] << '\\n';

     numbers[0] = 5;

     std::cout << "All numbers:";
     for (auto i : numbers)
         std::cout << ' ' << i;
     std::cout << '\\n';
 }

.SH Output:

 Second element: 4
 All numbers: 5 4 6 8

.SH See also

   at access specified element with bounds checking
      \fI(public member function)\fP
